SREL Reprint #2900
Experimental evidence that nest attendance benefits female marbled salamanders (Ambystoma opacum) by reducing egg mortality
Dean A. Croshaw1,2 and David E. Scott1
1Savannah River Ecology Laboratory, Drawer E, Aiken, South
Carolina 29802
2Department of Zoology, University of Oklahoma, Norman 73019
Abstract:
To understand the selective pressures that have influenced the
evolution and maintenance of parental care, it is necessary to assess
the consequences and function(s) of specific behaviors. We used field
and laboratory experiments to investigate possible fitness benefits and
proximate functions of female nest attendance in marbled salamanders (Ambystoma
opacum). In the first field experiment, nests at which females remained
until flooding had higher hatching success than those without attendant
females, but results were somewhat equivocal. In the second field experiment
we used unattended eggs in artificial
clutches randomly assigned to one of four treatment groups: eggs physically
agitated to possibly reduce developmental malformations and/or fungal
growth, eggs protected from predators, eggs moistened by addition of water
and eggs in an unmanipulated control group. Clutches that were protected
from predators had significantly higher hatching success than control,
agitation and supplemental water groups. In the laboratory experiment,
nests in which fungal infection was controlled had higher hatching success
than those without sterilized substrates. Also, physical agitation and
increased moisture did not confer higher hatching success when fungi were
eliminated in the laboratory. Predation and fungal infections appear to
decrease hatching success in this species, and female nest attendance
may reduce these risks.
SREL Reprint #2900
Croshaw, D. A. and D. E. Scott 2004. Experimental evidence that nest attendance benefits female marbled salamanders (Ambystoma opacum) by reducing egg mortality. The American Midland Naturalist 154:398-411.